Shell Scripts

• Remote Operating System (ROS) - from Attrition.org
• Log Rotate - from Attrition.org

Perl Scripts

• Earlybird - Bite back at NIMDA
• Calamaris - Parse Squid proxy logs and generate reports
• NMS - CGI scripts with an emphasis on security
• Matt's Script Archive
• File System Saint - Host-based Intrusion Detection

Programs

• Apache - The web server for unix
• Squid - Proxy server
• Qmail - A secure alternative to Sendmail
• EZMLM - A mailing list manager for Qmail
• Majordomo - A mailing list manager for Sendmail
• NMAP - Simply the best network scanner/mapper out there
• djbdns - DNS tools & services you shouldn't live without
• Snort - Network based Intrusion Detection
• Nessus - Vulnerability scanning
• Webalizer - Web statistics reporting
• GNU wget - Retrieve files via common internet protocols

Tidbits

• checkpassword-krb5.c - A checkpassword program that authenticates against a Kerberos KDC.
• rejectrcpt_cdb.patch - A variant on badrcptto (qmail) that uses a CDB format for faster lookups.